docs: def wave_range(self, cenwave, npix, waveunits=None, round='round'):
          """Get the wavelength range covered by the given number of pixels
          centered on the given wavelength.
  
          .. note::
  
             This calls :func:`wave_range` with ``self.binset``
             as the first argument.
  
          Parameters
          ----------
          cenwave, npix, round
              See :func:`wave_range`.
  
          waveunits : str, optional
              Wavelength units of ``cenwave`` and the returned wavelength range.
              If `None` (default), the wavelengths are assumed to be in
              the units of ``self.waveunits``.
  
          Returns
          -------
          waverange : tuple of floats
              The range of wavelengths spanned by ``npix`` centered on
              ``cenwave``.
  
          Raises
          ------
          pysynphot.exceptions.UndefinedBinset
              If ``self.binset`` is None.
  
          """
          # make sure we have a binset to work with
          if self.binset is None:
              raise exceptions.UndefinedBinset('No binset specified for this bandpass.')
  
          # convert cenwave from waveunits to self.waveunits, if necessary
          if waveunits is not None:
              waveunits = units.Units(waveunits)
  
              # convert to angstroms and then whatever self.waveunits is
              cenwave = waveunits.ToAngstrom(cenwave)
              cenwave = units.Angstrom().Convert(cenwave, self.waveunits.name)
  
          wave1, wave2 = wave_range(self.binset, cenwave, npix, round=round)
  
          # translate ends to waveunits, if necessary
          if waveunits is not None:
              # convert to angstroms
              wave1 = self.waveunits.ToAngstrom(wave1)
              wave2 = self.waveunits.ToAngstrom(wave2)
  
              # then to waveunits
              wave1 = units.Angstrom().Convert(wave1, waveunits.name)
              wave2 = units.Angstrom().Convert(wave2, waveunits.name)
  
          return wave1, wave2